1. Field of the Invention
This invention pertains to an implant for passing blood flow directly between a chamber of the heart and a coronary vessel. More particularly, this invention pertains to such an implant with an enhance design for reducing a likelihood of damage to a coronary vessel from a high-velocity blood flow discharge.
2. Description of the Prior Art
Commonly assigned U.S. Pat. No. 5,755,682 and PCT International Publication No. WO 98/06356 teach an implant for defining a blood flow conduit directly from a chamber of the heart to a lumen of a coronary vessel. An embodiment disclosed in the aforementioned patent and application teaches an L-shaped implant. The implant is a conduit having one leg sized to be received within a lumen of a coronary artery and a second leg sized to pass through the myocardium and extend into the left ventricle of the heart. As disclosed in the above-referenced patent and application, the conduit remains open for blood flow to pass through the conduit during both systole and diastole. The conduit penetrates into the left ventricle in order to prevent tissue growth and occlusions over an opening of the conduit.
Commonly assigned and co-pending U.S. patent application Ser. No. 08/944,313 filed Oct. 6, 1997, entitled xe2x80x9cTransmyocardial Implantxe2x80x9d, filed in the name of inventors Katherine S. Tweden, Guy P. Vanney and Thomas L. Odland, issued as U.S. Pat. No. 5,984,956 on Nov. 16, 1999, teaches an implant such as that shown in the aforementioned xe2x80x98682 patent with an enhanced fixation structure. The enhanced fixation structure includes a fabric surrounding at least a portion of the conduit to facilitate tissue growth on the exterior of the implant.
Implants such as those shown in the aforementioned patent and applications include a portion to be placed within a coronary vessel and a portion to be placed within the myocardium. When placing a portion of the implant in the coronary vessel, the vessel is incised a length sufficient to insert the implant. When placed within the coronary vessel, the implant discharges flow axially into the vessel. A portion of an interior surface of the implant portion in the vessel acts as a deflection surface to prevent direct impingement of high velocity blood flow on a vessel wall.
The L-shaped implant described in the foregoing is preferably placed through a surgical procedure (open chest or minimally invasively). The suitability of an implant for minimally invasive or percutaneous procedures is influenced, at least in part, by the external size and shape of the implant. The size can be reduced and shape enhanced by elimination of the vessel portion of the foregoing designs.
According to a preferred embodiment of the present invention, a transmyocardial implant is disclosed for establishing a blood flow path through a heart wall between a heart chamber and a lumen of a coronary vessel on the heart wall. The implant includes a hollow conduit having an open first end and an open second end. The conduit is dimensioned so as to extend at least from the vessel through said heart wall and into said chamber. The conduit has a conduit wall defining a blood flow pathway within an interior of said conduit between the first and second ends. The first and second ends are mutually positioned for the first end to reside within the vessel and opposing a wall of the vessel when the conduit is placed within the heart wall with the second end protruding into the chamber. The conduit wall is formed of a material sufficiently rigid to resist deformation and closure of the pathway in response to contraction of the heart wall. A flow restriction is formed in the pathway for reducing a discharge velocity of blood flow discharged from the first end.